| Abstract: | A 40-50-mgal gravity low trends northeast along the Colorado mineral belt between Monarch Pass and Breckenridge, Colorado. The low is probably caused by a silicic Tertiary batholith of lower density than adjacent Precambrian crystalline rocks. Many major mining districts associated with silicic Tertiary intrusives are near the axis of the low.
Positive and negative aeromagnetic anomalies are present over the larger silicic Tertiary intrusive bodies. A good correlation exists between the magnetic lows and zones of altered, mineralized porphyry. Apparently, original magnetite in the silicic porphyries has been altered to relatively nonmagnetic pyrite or iron oxides.
The regional gravity low aids in defining the limits of the mineral belt, and the magnetic lows over the porphyries indicate specific alteration zones and the possibility of associated mineral deposits. |
| Genre: | USGS Numbered Series |
| ProdID: | 12933 |
| Citation Author: | Case, James E. |
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| Citation Language: | ENGLISH |
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| Citation Phsyical Description: | 13 p. ill., maps ;28 cm. |
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| Citation Publisher: | U.S Geological Survey], |
| Citation Series: | Open-File Report |
| Citation Series Code: | OFR |
| Citation Series Number: | 67-39 |
| Citation Search Results Text: | Geophysical ore guides along the Colorado mineral belt; 1967; OFR; 67-39; Case, James E. |
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| Citation Year: | 1967 |
| Type: | citation/reference |
| Text: | Geophysical ore guides along the Colorado mineral belt; 1967; OFR; 67-39; Case, James E. |
| URL (THUMBNAIL): | http://pubs.usgs.gov/of/1967/0039/report-thumb.jpg |
| URL (DOCUMENT): | http://pubs.usgs.gov/of/1967/0039/report.pdf |
| Date Other: | Sat, 1 Jan 1994 00:00 -0600 |
| Publisher: | U.S Geological Survey], |
